76 HEAD AND NECK 



capitis posterior minor crosses the superficial surface of the 

 rectus capitis posterior major ; the last branch passes down- 

 wards to the inferior oblique muscle ; it supplies that muscle 

 and sends a twig of communication to the greater occipital nerve, 

 which in its turn sends a communicating twig to the medial 

 branch of the posterior ramus of the third cervical nerve. The 

 union of the posterior rami of the first three cervical nerves thus 

 formed is called the posterior cervical plexus. After the nerves 

 mentioned have been secured and cleaned, clean the muscles 

 which form the boundaries of the space, and afterwards remove 

 the remains of the fascia from the space, and display the posterior 

 arch of the atlas, the third portion of the vertebral artery, which 

 lies on the upper surface of the posterior arch of the atlas above 

 the trunk of the sub-occipital nerve, and the posterior atlanto- 

 occipital ligament. 



Musculus Rectus Capitis Posterior Major. The major 

 posterior rectus muscle of the head springs by a pointed origin 

 from the spine of the epistropheus (O.T. axis), and expanding 

 as it passes upwards and laterally, it is inserted into the occipital 

 bone along the lateral portion of the inferior nuchal line and 

 into the surface immediately below. It draws the head 

 backwards and rotates it to the same side. It is supplied by 

 the posterior ramus of the sub-occipital nerve. 



Musculus Rectus Capitis Posterior Minor. The minor 

 rectus capitis posterior muscle is a small fan-shaped muscle, 

 placed to the medial side of, and overlapped by, the rectus 

 major. It takes origin from the tubercle on the posterior 

 arch of the atlas, and is inserted into the medial part of the 

 inferior nuchal line of the occipital bone and into the surface 

 between that line and the foramen magnum. It draws the 

 head backwards and is supplied by the posterior ramus of 

 the sub-occipital nerve (Fig. 20). 



Musculus Obliquus Capitis Inferior. The inferior oblique 

 muscle extends from the extremity of the spine of the 

 epistropheus to the posterior border of the transverse process 

 of the atlas. The greater occipital nerve will be seen hooking 

 round its lower border. It is supplied by the posterior ramus 

 of the sub-occipital nerve and it rotates the atlas and the 

 head to the same side. 



Musculus Obliquus Capitis Superior. The superior oblique 

 muscle springs from the transverse process of the atlas, and is 

 inserted into the occipital bone, in the interval between the 

 nuchal lines, below and to the lateral side of the semispinalis 

 capitis. Acting with its fellow of the opposite side it draws 

 the head backwards. Acting alone it turns the head slightly 



